<template>
    <!-- 商品分类导航 -->
    <div class="type-nav">
        <div class="container">

            <div @mouseleave="leaveIndex" @mouseenter="enterShow">
                <h2 class=" all">全部商品分类</h2>
                <transition name="sort">
                    <div class="sort" v-show="show">
                        <div class="all-sort-list2" @click="goSearch"> <!--不知为啥数据有17 -->
                            <div class="item" v-for="(c1, index) in categoryList.slice(0, 16)" :key="c1.categoryId"
                                :class="{ cur: currentIndex === index }">

                                <h3 @mouseenter="changeIndex(index)"> <!-- 鼠标移到谁，就传他的index -->
                                    <a :data-categoryName="c1.categoryName" :data-category1Id="c1.categoryId">{{
                                        c1.categoryName }}</a>
                                </h3>
                                <div class="item-list clearfix"
                                    :style="{ display: currentIndex === index ? 'block' : 'none' }">
                                    <div class="subitem" v-for="c2 in c1.categoryChild" :key="c2.categoryId">
                                        <dl class="fore">
                                            <dt>
                                                <a :data-categoryName="c2.categoryName"
                                                    :data-category2Id="c2.categoryId">{{ c2.categoryName }}</a>
                                            </dt>
                                            <dd>
                                                <em v-for="c3 in c2.categoryChild" :key="c3.categoryId">
                                                    <a :data-categoryName="c3.categoryName"
                                                        :data-category3Id="c3.categoryId">{{ c3.categoryName }}</a>
                                                </em>

                                            </dd>
                                        </dl>
                                    </div>
                                </div>
                            </div>

                        </div>
                    </div>
                </transition>
            </div>

            <nav class="nav">
                <a href="###">服装城</a>
                <a href="###">美妆馆</a>
                <a href="###">尚品汇超市</a>
                <a href="###">全球购</a>
                <a href="###">闪购</a>
                <a href="###">团购</a>
                <a href="###">有趣</a>
                <a href="###">秒杀</a>
            </nav>

        </div>
    </div>
</template>

<script>
import { mapState } from "vuex";
import throttle from 'lodash/throttle'//按需引入节流函数


export default {
    name: "TypeNav",
    mounted() {
        // console.log(this.categoryList)
        if (this.$route.path !== "/home") {
            this.show = false
        }
    },
    data() {
        return {
            currentIndex: -1,
            show: true,
        }
    },
    computed: {
        ...mapState(//对象写法
            {
                categoryList: (state) => {
                    return state.home.categoryList//打印一下state参数就知道为啥要怎么写了
                }
            }
        )
    },
    methods: {      //别用箭头函数，可能出现上下文this问题
        changeIndex: throttle(function (index) {//使用节流函数，throttle默认暴露不用_.throttle
            //   console.log(index);
            this.currentIndex = index
        })
        ,
        leaveIndex() {
            this.currentIndex = -1
            if (this.$route.path !== "/home")
                this.show = false
        },
        goSearch(event) {
            let element = event.target
            //注意大小写，浏览器回自动全变为小写
            let { categoryname, category1id, category2id, category3id } = element.dataset//解构赋值
            console.log(element.dataset);


            let location = {
                path: "/search"
            }
            let query = {
                categoryName: categoryname
            }
            if (categoryname) {
                if (category1id) {
                    query.category1Id = category1id
                } else if (category2id) {
                    query.category2Id = category2id
                } else {
                    query.category3Id = category3id
                }
            }

            if (this.$route.params)
                location.params = this.$route.params

            location.query = query

            //路由跳转
            this.$router.push(location)//传一个对象，会自动找path路径
        },
        enterShow() {
            if (this.$route.path !== "/home")
                this.show = true
        }
    }
}
</script>

<style lang="less" scoped>
.type-nav {
    border-bottom: 2px solid #e1251b;

    .container {
        width: 1200px;
        margin: 0 auto;
        display: flex;
        position: relative;

        .all {
            width: 210px;
            height: 45px;
            background-color: #e1251b;
            line-height: 45px;
            text-align: center;
            color: #fff;
            font-size: 14px;
            font-weight: bold;
        }

        .nav {
            a {
                height: 45px;
                margin: 0 22px;
                line-height: 45px;
                font-size: 16px;
                color: #333;
            }
        }

        .sort {
            position: absolute;
            left: 0;
            top: 45px;
            width: 210px;
            height: 461px;
            position: absolute;
            background: #fafafa;
            z-index: 999;

            .all-sort-list2 {
                .item {
                    h3 {
                        line-height: 30px;
                        font-size: 14px;
                        font-weight: 400;
                        overflow: hidden;
                        padding: 0 20px;
                        margin: 0;

                        a {
                            color: #333;
                        }
                    }

                    .item-list {
                        display: none;
                        position: absolute;
                        width: 734px;
                        min-height: 460px;
                        background: #f7f7f7;
                        left: 210px;
                        border: 1px solid #ddd;
                        top: 0;
                        z-index: 9999 !important;

                        .subitem {
                            float: left;
                            width: 650px;
                            padding: 0 4px 0 8px;

                            dl {
                                border-top: 1px solid #eee;
                                padding: 6px 0;
                                overflow: hidden;
                                zoom: 1;

                                &.fore {
                                    border-top: 0;
                                }

                                dt {
                                    float: left;
                                    width: 54px;
                                    line-height: 22px;
                                    text-align: right;
                                    padding: 3px 6px 0 0;
                                    font-weight: 700;
                                }

                                dd {
                                    float: left;
                                    width: 415px;
                                    padding: 3px 0 0;
                                    overflow: hidden;

                                    em {
                                        float: left;
                                        height: 14px;
                                        line-height: 14px;
                                        padding: 0 8px;
                                        margin-top: 5px;
                                        border-left: 1px solid #ccc;
                                    }
                                }
                            }
                        }
                    }


                }

                .cur {
                    background-color: skyblue;
                }
            }
        }

        //过渡动画
        .sort-enter {
            height: 0px;

        }

        .sort-enter-to {
            height: 461px;

        }

        .sort-enter-active {
            transition: all 1s linear;
        }
    }

}
</style>
